Photographic materials and processes

ABSTRACT

PHOTOGRAPHIC MATERIALS ARE PROVIDED WHICH COMPRISE A SUPPORT HAVING COATED THEREON AN IMAGE DYE-PROVIDING LAYER UNIT CONTAINING A LIGHT-SENSITIVE PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER COMPRISING UP TO ABOUT 320 MG. SILVER PER SQUARE METER, A PHOTOGRAPHIC COLOR COUPLER COATED AT A CONCENTRATION OF AT LEAST TWO TIMES THE WEIGHT OF THE SILVER AND A HYDROPHILIC COLLOID BINDER FOR THE SILVER HALIDE AND COUPLER COATED AT A COVERAGE OF FROM ABOUT 215 TO 970 MG. PER SQUARE METER, THE WEIGHT RATIO OF SILVER TO HYDROPHILIC COLLOID BEING FROM 1:2 TO 1:20 AND THE WEIGHT RATIO OF COUPLER TO HYDROPHILIC COLLOID BINDER BEING FEROM 1: 1/2. THE PHOTOGRAPHIC ELEMENTS OF THE INVENTION ARE PREFERABLY PROCESSED IN A DEVELOPER SOLUTION COMPRISING A PHOTOGRAPHIC COLOR-DEVELOPING AGENT AND AN OXIDIZING AGENT SUCH AS A COBALT COMPLEX WHICH UNDERGOES REDOX REACTION WITH THE COLORDEVELOPING AGENT IN THE PRESENCE OF METALLIC SILVER.

United States Patent 3,822,129 PHOTOGRAPHIC MATERIALS AND PROCESSESJoseph S. Dunn and Rowland G. Mowrey, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester, N.Y.

No Drawing. Continuation-impart of abandoned application Ser. No.189,330, Oct. 14, 1971. This application Aug. 31 ,1972, Ser. No. 285,399

. Int. Cl. G03c 1/40 US. Cl. 96-60 R 26 Claims ABSTRACT OF THEDISCLOSURE Photographic materials are provided which comprise a supporthaving coated thereon an image dye-providing layer unit containing alight-sensitive photographic silver halide emulsion layer comprising upto about 320 mg. silver per square meter, a photographic color couplercoated at a concentration of at least two times the weight of the silverand a hydrophilic colloid binder for the silver halide and couplercoated at a coverage of from about 215 to 970 mg. per square meter, theweight ratio of silver to hydrophilic colloid :being from 1:2 to 1:20and the weight ratio of coupler to hydrophilic colloid binder being from1: /2 to 1:2. The photographic elements of the invention are preferablyprocessed in a developer solution comprising a photographiccolor-developing agent and an oxidizing agent such as a cobalt complexwhich undergoes redox reaction with the colordeveloping agent in thepresence of metallic silver.

This application is a continuation-in-part of US. Ser. No. 189,330 filedOct. 14, 1971, now abandoned.

This invention relates to photographic materials and processes. In oneaspect, this invention relates to improved photographic elements whichcontain light-sensitive silver halide layers having low coverages ofsilver halides. In another aspect, this invention relates tophotographic elements comprising at least one image dyeproviding layerunit which contains a light-sensitive silver halide, a color coupler anda hydrophilic colloid in a ratio to coupler of less than 2:1(colloid:coupler).

Photographic elements containing a light-sensitive silver halide layerwith relatively low coverages of silver have been described in theliterature. US. Pat. 2,614,808 by Dimsdale and 2,173,737 by Weberdisclose methods for intensifying the silver image in a photographic element. More recently disclosures have appeared in Belgian Pat. 742,768 ofJune 8, 1970, and British Pat. 1,268,126 of photographic elementscontaining a layer of a silver halide emulsion at a coverage of 50 to200 mg. of silver per square meter.

Bissonette in US. Patent Application Ser. No. 189,289 filed Oct. 14,1971, entitled Image-Forming Photographic Processes and Compositionsdescribes inter alia processes for amplifying silver images inlight-sensitive silver halide emulsions layers containing photographiccolor coupler ,which features the use of developer solutions containingphotographic aromatic primary amine colordeveloping agent together withcertain oxidizing agents, for example, cobalt hexammine (III) chlorideor other metal complexes having similar reactivity. The proceduresdescribed in the Bissonette application are suitable for use in theamplification of photographic elements comprising light-sensitive silverhalide emulsion layers coated at low silver coverages and containingcolor coupler.

While the photographic elements referred to above which contain lowsilver coverages can produce good results, it wouldbe desirable iffurther modifications could be made in such elements, and the processing3,822,129 Patented July 2, 1974 thereof, to increase speed, decreasefog, improve incubation stability before exposure and processing,provide more stable dye images and improve image structure, par-;icularly with regard to sharpness and reduced granuarity.

One object of this invention is to provide photographic elements whichhave silver halide coated at low silver coverages which exhibitincreased speed.

Another object of this invention is to provide photographic elementswhich have low silver coverages which exhibit reduced fog.

A further object of this invention is to provide photographic elementswhich have low coverages of silver halide and which produce sharp dyeimages which have relatively low granularity.

\A further object of this invention is to provide a process forobtaining dye images which are sharp and which have low granularity,from photographic elements which contain silver halide emulsion layerscoated at low silver coverages.

Another object of this invention is to increase the rate at whichmulticolor photographic elements can be developed.

Still another object of this invention is to provide a process forobtaining reducedfog and increased speed in photographic silver halideemulsions coated at low coverages of silver halide.

Another object of this invention is to provide photographic elements andprocesses which produce dye images having good stability.

Still other objects of this invention will be apparent from thisdisclosure and the appended claims.

In accordance with this invention an improvement is provided inphotographic elements comprising a support having coated thereon atleast one image dye-providing layer unit containing a light-sensitivephotographic silver halide emulsion coated at a coverage of up to 320mg. silver per square meter and a photographic color coupler at aconcentration of at least two times the weight of the silver. Theimprovement in accordance with this invention is achieved by employing ahydrophilic colloid binder for the silver halide and coupler at aconcentration of from about 215 to 970 mg. per square meter andmaintaining a weight ratio of coupler to hydrophilic colloid in saidimage dye-providing layer unit of from about 1: /2 to 1:2, and a weightratio of silver to hydrophilic colloid of from 1:2 to 1:20. Thereduction in the amount of hydrophilic colloid employed over the levelsheretofore suggested in the prior art results in substantial improvementin image structure, particularly with respect to improved sharpness,reduced granularity and better heat stability. In addition, photographicelements in accordance with the invention typically exhibit reduced lowfog, improved aging properties, increased speed and developabilitycompared with corresponding elements containing conventional bindercoverages of over 1080 mg.

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' per square meter. These results are particularly surprising sincephotographic elements containing conventional concentrations of silverhalide (typically in excess of about 1080 mg. silver per square meter),together with color coupler at levels of from about two to ten times theamount of silver, fail to show significant increases in speed,developability, reduced fog or better image structure when theconcentration of hydrophilic colloid is lowered and the elements areprocessed in conventional color processes.

The photographic elements of this invention can be processed to provideimage records by several procedures.

In a highly preferred embodiment, the photographic elements canbeprocessed to provide an image record by the procedures described inaforementioned copending application U.S. Ser. No. 189,289, entitledIrnage- Forming Process and Compositions filed Oct. 14, 1971, andincorporated herein by reference. In one embodiment of this process, theimagewise-exposed element is contacted with a photographiccolor-developing agent and an oxidizing agent, such as a cobalt(III)metal complex having a coordination number of 6, until the desired dyedensity is obtained. The cobalt metal complex is apparently reduced tocobalt(II) in the presence of silver, which appears to act as acatalyst, and the color developer is oxidized whereby it can react withthe color coupler in each respective layer unit to form the desiredimage dye. The formation of oxidized developer can continue as long asthere is a suflicient supply of the metal complex and color developer inthe presence of the ilver catalyst.

In another highly preferred process, a photographic element inaccordance with this invention is processed as disclosed by Travis, U.S.Ser. No. 256,071 filed May 23, 1972, entitled Process for DevelopingPhotographic Elements, now U.S. Pat. 3,765,891. In this process thephotographic element in accordance with this invention which has beenimagewise-exposed is developed to convert the developable silver halideinto metallic silver and form image dye. With negative emulsions theexposed areas will be developable, whereas with direct-positiveemulsions or reversal emulsions the unexposed areas will be developed.The photographic element containing undeveloped silver halide and animagewise distribution of metallic silver is then contacted with asuitable metal complex, such as a cobalt(III) complex having acoordination number of 6, in the presence of a color-developing agentwhich is preferably imbibed into the element during the colordevelopmentstep and carried into the bath containing the cobalt metal complex. Thecolor-developing agent can be the same developing agent used to convertthe latent image to silver and remain in the coating in transit to thetreatment with the metal complex or the color developer can be providedafter formation of the silver. Preferably, the photographic element istreated with a liquid bath containing the suitable metal complex andwhich also contains a silver halide development restrainer, thusallowing this step to proceed in roomlight. By using this process onecan observe the dye formation and stop dye formation at the desired dyedensity.

The elements of this invention can also be processed by using a physicaldeveloping agent such as described in Dipple et al., U.S. Pat. 2,750,292issued June 12, 1956. By treating imagewise-exposed elements of thisinvention with a solution containing only the color-developing agent andthe physical developing agent, rather than the solution described byDipple et al., it is possible, to obtain the multicolor image record.

Additionally, the elements of this invention can be developed by using avariation of the process described in Weber, U.S. Pat. 2,173,739. Theelements of this invention which have been imagewise-exposed can bedeveloped in a color developer to produce a low-density dye, bleachedpartially with a solution as described in Weber, such as a potassiumferricyanide bleach, redeveloped in color developer to intensify theimage, etc., until the desired dye density is obtained. Peroxytreatments such as used in British Pat. 1,268,126 could also be adaptedin a manner similar to the next above process for use in development ofa multicolor element according to this invention.

In still another embodiment, the elements of this invention can bedesigned for use in and can be processed by the color negative or colorreversal processes referred to in U.S. Pat. 3,046,129 by Graham issuedJuly 24, 1962, 3,547,640 by Beckett, and 2,944,900.

The present invention is particularly suitable with multilayer,multicolor photographic elements comprising a support having coatedthereon silver halide emulsion layers sensitive to blue, green and redradiation and which contain, respectively, yellow, magenta and cyandyeforming photographic couplers. Preferably, at least the greenandred-sensitive layers are coated at the low silver and hydrophiliccolloid binder coverages described herein. In certain preferredembodiments of the invention, all three layers contain the silver,coupler and hydrophilic binder coverages and ratios featured in thisinvention. Particularly useful are photographic elements which have awhite-reflective support and which have coated thereon, in the ordergiven, blue-, greenand red-sensitive silver halide emulsion layers. Thelayers in the multilayer photographic elements described herein can beseparated by conventional hydrophilic colloid interlayers or protectiveovercoating layers, and such layers can contain various other usefuladdenda, such as ultraviolet absorbers.

Cyan dyes formed in layers having low coverages of hydrophilic colloidexhibit a surprising increase in heat stability over cyan dye imagesformed in prior-art layers having conventional coverages of hydrophiliccolloid. Most yellow and magenta photographic dyes deteriorate fasterthan cyan dyes in the presence of oxygen. Hence, an especially preferredembodiment of the invention features photographic elements in which theyellow and magenta dyes are formed in layers between the support and thelayer which forms the cyan dye. A relatively thick interlayer, such as ahydrophilic colloid layer coated at about 3230 mg. per square meter, canbe present between the cyan dye-forming layer and the underlying yellowand magenta dye-forming layers. This thick interlayer protects theyellow and magenta dyes from oxygen-induced deterioration.

In one preferred embodiment of the invention, the total quantity ofhydrophilic colloid in the silver halide-containing, image dye-providinglayer units is less than about 3230 mg., and preferably less than about2700 mg., hydrophilic colloid per square meter.

The coverage of the hydrophilic colloid interlayers and overcoatings canvary over a wide range. Generally, the most useful range is from about540 to 1080 mg. of hydrophilic colloid per square meter althoughsomewhat higher coverages, on the order of from about 1600 to 3230 mg.per square meter, are sometimes desirable when substantial quantities ofultraviolet absorber are to be included in the layer.

The multilayer, multicolor photographic elements of this inventionadvantageously contain a total of less than about 8100 and morepreferably less than about 7000 mg. of hydrophilic colloid binder persquare meter. This represents reductions of nearly 50%, in both thetotal amount of hydrophilic colloid and in the image dye-pro vidinglayer units, over the quantities of hydrophilic colloid employed intypical photographic color papers which are in commercial use.

As indicated above, the silver halide emulsions are coated in accordancewith this invention at silver coverages of up to about 320 mg. silverper square meter, such as from 11 to 320 mg. per square meter orpreferably a from about 11 to 270 mg. silver per square meter.Especially good results are obtained with coverages on the order of fromabout 22 up to about or mg. per square meter of silver for the greenandred-sensitive layers in typical multilayer color films.

In certain embodiments of this invention, the silver halide is coated atcoverages less than that which will give undesirable background images,thus avoiding the necessity of bleaching or fixing. In theseembodiments, the silver halide is coated at a coverage less than thatamount which, if the silver halide were fully exposed and developed,would result in a maximum silver density less than 0.4, and preferablyless than 0.2 (such as by using silver halide at silver coverages ofless than about 215 and preferably less than 110 mg. per square meter).

Thea photographic elements of this invention contain at least sufiicientsilver halide to provide a latent image, or at least photolytic silver,upon imagewise exposure.

In one preferred embodiment, the photographic elements of this inventioncomprise an image dye-providing layer unit wherein the silver halide andthe coupler are coated together with the hydrophilic colloid as onelayer. Preferably, the photographic element contains threeseparateimage-recording layers with one layer containing silver halide having aneffective blue sensitivity, one layer containing silver halide having aneffective green sensi tivity and one layer containing silver halidehaving an effective red sensitivity. By effective sensitivity it isunderstood that the layer as incorporated in the element will recordlight in that region of the spectrum which may be accomplishd by use ofspectral-sensitizing dyes, filter layers, etc.

In another embodiment, the color couplers are coated in layers adjacentand preferably contiguous to the silver halide emulsion. In thisembodiment, the silver halide emulsion layer and the layer or layerscontaining the color coupler can be considered to function together toprovide an image dye-providing layer unit. Preferably, the silver halideemulsion layer has associated contiguous therewith a. coupler-containinglayer on each side thereof. In a typical multicolor photographic elementat least two image dye-providing layer units will be provided which eachrecord light dominantly in different regions of the light spectrum andhave color couplers associated therewith which will produce a dye havinga predominant VlSlble light absorption in the region of the visiblespectrum corresponding to the effective spectral sensitivity of theassociated silver halide emulsion. In this embodiment, the

dye image-providing layer unit contains the silver halide, coupler andhydrophilic colloid in the ratios specified 1n accordance with thisinvention. The image dye-providing layer units can be separated fromeach other by interlayers, barrier layers, etc. However, good imagediscrimination can be obtained where the respective image-dyeprovidinglayer units of a multicolor element are coated contiguous to each other.

Silver halide emulsions which can be used in the image dye-providinglayer units in accordance with this inven tion can comprise, forexample, silver chloride, silver bromide, silver bromoiodide, silverchlorobromide, silver chloroiodide, silver chlorobromoiodide crystals ormixtures thereof. The emulsions may be coarseor fine-grain emulsionsprepared by any of the Well-known techniques, e.g., single-jet emulsionssuch as those described in Trivelli and Smith, The Photographic Journal,vol. LXXDC, May, 1939 (pp. 330-338), double-jet emulsions such asLippmann emulsions, ammoniacal emulsions, thiocyanate or thioetherripened emulsions such as those described in U.S. Pats. 2,222,264 byNietz et al. issued Nov. 19, 1940, 3,320,069 by Illingsworth issued May16, 1967, and 3,271,- 157 by McBride issued Sept. 6, 1966. Surface-imageemulsions may be used or internal-image emulsions may be used such asthose described in U.S. Pats. 2,592,250 by Davey et al. issued May8,1952, 3,206,313 by Porter et al. issued Sept. 14, 1965, 3,367,778 byBerriman issued Feb. 6, 1968, and 3,447,927 by Bacon et al. issued June3, 1969. If desired, mixtures of surfaceand internal-image emulsions maybe used as described in U.S. Pat. 2,996,- 382 by Luckey et al. issuedAug. 15, 1961. The emulsions may be regular-grain emulsions such as thetype described in Klein and Moisar, J. Phot. Sci., vol. 12, No. 5,Sept./ Oct., 1964, pp. 242-251. Negative-type emulsions may be used ordirect-positive emulsions may be used such as those described in U.S.Pats. 2,184,013 by Leermakers issued Dec. 19, 1939, 2,541,472 by Kendallet al. issued Feb. 13, 1951, 3,367,778 by Berriman issued Feb. 6, 1968,3,501,307 by Illingsworth issued Mar. 17, 1970, 2,563,785 by Ives issuedAug. 7, 1951, 2, 456,953 by Knott et al. issued Dec. 21, 1948, and2,861,885 by Land issued Nov. 25, 1958, British Pat. 723,019 bySchouwenaars issued Feb. 2, 1955, and French Pat. 1,520,821 byIllingsworth et al. issued Mar. 4, 1968. Preferably, the emulsions arenegative, developing-out-type silver halide emulsions.

Generally, each of the color-providing layer units of the photographicelements of this invention contains a lightsensitive silver salt whichis preferably a silver halide. In one preferred embodiment, at least twoof the color-providing layer units each comprise a silver salt at aconcentration of up to 320 mg. of silver/mP. However, while thedevelopable silver is preferably present at concentrations based onsilver of less than 320 mg./m. it is possible to coat blended emulsionsat higher coverages within this embodiment as long as no more than 320mg./m. of silver develops; for example, such emulsions may containsilver halide grains which are relatively light-insensitive or maycontain development restrainers, such as development inhibitor-releasingcouplers, and still provide a photographic element which isadvantageously used in the various processes as described herein toproduce improved image records. In some instances, emulsions containingrelatively light-insensitive grains or development inhibitors aredesirable to enable one to obtain more uniform coating coverage withless precise coating equipment, as well as for other reasons. Thus,highly preferred photographic elements of this invention contain atleast two color-providing layer units, each containing a silver halideemul sions, defined in terms of effective coverage and developability asone which, when it is fully exposed and processed for about 1 minute atF. in Developer A, as follows:

Water to 1 liter pH 10.1 at 24 C.

will provide less than 320 mg. of metallic silver/m. and preferably lessthan mg./m. It is understood that the term effective silver refers tothat amount of silver which is developed in this test and that ratios ofcoupler to silver are based on effective silver which is produced bythis type of development when so specified herein. In most instances,the quantity of effective silver as silver halide in the undeveloped,unexposed photographic element will be quite similar to quantity oftotal silver present as silver halide. The fully exposed layercontaining silver halide emulsion is one which is exposed to Dmax as iswell-known in the art, for example, by exposure to a SOO-Watt, 3000 K.lamp for about 10 seconds (total exposure at the film plane=11.3 10ergs./cm.

Photographic color couplers are employed in accordance with theinvention at a concentration of at least 2 times, such as from 3 to 20times, the weight of the silver in the silver halide emulsion. Weightratios of conpler-to-silver coverage which are particularly useful arefrom 3 to 15 parts by weight coupler to 1 part by weight silver.Advantageously, the coupler is present in an amount sufficient to give adensity of at least 1.7 and preferably at least 2.0. Preferably, thedifference between the maximum density and the minimum density (whichcan comprise unbleached silver) is at least .6 and preferably at least1.0.

As used herein, the term photographic color coupler includes anycompound which reacts (or couples) with the oxidation products ofprimary aromatic amino develop ing agent on photographic development toform a dye, and are nonditfusible in a hydrophilic colloid binder (e.g.,gelatin) useful for photographic silver halide. The couplers can formdiffusible or non-diifusible dyes. Typical useful color couplers includephenolic, S-pyrazolone and openchain ketomethylene couplers. Specificcyan, magenta and yellow color couplers which can be employed in thepractice of this invention are described in Graham et al., U.S. Pat.3,046,129 issued Jan. 24, 1962, column 15, line 45, through column 18,line 51, which disclosure is incorporated herein by reference. Suchcolor couplers can be dispersed in any convenient manner, such as byusing the solvents and the techniques described by U.S. Pats. 2,322,-027 by Jelley et al. issued June 15, 1943, or 2,801,171 by Fierke et al.issued July 30, 1957. When coupler solvents are employed, the mostuseful weight ratios of color coupler-to-coupler solvent range fromabout 1:3 to 1:0.1. The useful couplers include Fischer-typeincorporated couplers such as those described in Fischer, U.S. Pat.1,055,155 issued Mar. 4, 1913, and particularly nondifiusibleFischer-type couplers containing branch carbon chains, e.g., thosereferred to in the references cited in Frohlich et al., U.S. Pat.2,376,679 issued May 22, 1945, column 2, lines 50-60. Particularlyuseful in the practice of this invention are the nondilfusible colorcouplers which form nondiifusible dyes.

In one highly preferred embodiment of the invention, the photographicelements comprise a support having thereon at least one imagedye-providing layer unit containing a light-sensitive silver salt,preferably silver halide, having associated therewith a stoichiometricexcess of coupler of at least 40 percent and at least preferably 70percent. The equivalency of color couplers is known in the art; forexample, a 4-equivalent coupler requires 4 moles of oxidized colordeveloper, which in turn requires development of 4 moles of silver, toproduce 1 mole of dye. Thus, for a stoichiometric reaction with silverhalide, l-equivalent weight of this coupler will be 0.25 mole. Inaccordance with this invention, the color image-providing unit comprisesat least a 40 percent excess of the equivalent weight of imagedye-providing color coupler required to react on a stoichiometric basiswith the developable silver and preferably a 70 percent excess of saidcoupler. In one highly preferred embodiment, at least a 110 percentexcess of the coupler is present in said dye imageproviding layers basedon silver. Preferably, the couplerto-silver ratio is based on effectivesilver as defined herein. The ratio can also be defined as an equivalentexcess with a coupler-to-silver ratio of at least 1.4:1, and preferablyat least 1.7:1 (i.e., 2:1 being a 100 percent excess). In certainpreferred embodiments, the photographic color couplers are employed inthe image dye-providing layer units at a concentration of at least 3times, such as from 3 to times, the weight of the silver in the silverhalide emulsion. Weight ratios of coupler-to-silver coverage which areparticularly useful are from 4 to 15 parts by weight coupler to 1 partby weight silver. Advantageously, the coupler is present in an amountsufiicient to give a density of at least 1.7 and preferably at least2.0. Generally, the couplers utilized in the elements of this inventionwill have an equivalent weight of less than 1500 and preferably lessthan 1000 (i.e., molecular weight divided by number of functionalcoupling sites).

It is realized that the density of the dye may vary with the developingagent combined with the respective coupler, and accordingly the quantityof coupler can be adjusted to provide the desired density. Preferably,each layer unit contains at least 1X1O- moles/m. of color coupler.

Advantageously, the photographic color couplers utilized are selected sothat they will give a good neutral dye image. Preferably, the cyan dyeformed has its major visible light absorption between about 600 and 700nm., the magenta dye has its major absorption between about 500 and 600nm., and the yellow dye has its major absorption between about 400 and500 nm.

The term nondiffusible used herein as applied to couplers and productsderived from couplers has the meaning commonl applied to the term incolor photography and denotes materials which for all practical purposesdo not migrate or Wander through photographic hydrophilic colloidlayers, such as gelatin, particularly during processing in aqueousalkaline solutions. The same meaning is attached to the term immobile.The terms ditfusible and mobile have the converse meaning.

The light-sensitive silver halide grains and photographic color couplerscan be dispersed in colloids, which can be employed alone or incombination. Suitable hydrophilic materials include both naturallyoccurring substances such as proteins, for example, gelatin, gelatinderivatives, cellulose derivatives, polysaccharides such as dextran, gumarabic and the like, and synthetic polymeric substances such aswater-soluble polyvinyl compounds like poly (vinylpyrrolidone),acrylamide polymers and the like. Suitable thickening agents can beadded to the coating melts.

The described photographic emulsion layers and other layers of aphotographic element employed in the practice of this invention can alsobe used alone or in combination with other hydrophilic, water-permeablecolloids or synthetic polymeric compounds.

The light-sensitive layers of this invention are coated in such a mannerthat the hydrophilic colloid binder for the silver halide is coated at aconcentration less than about 1080 mg./m. such as about 215 to 970mg./m. or, preferably, from about 215 to 800 mg./m.

It is desirable to maintain a weight ratio of photographic color couplerto hydrophilic colloid of from about 1: /2 to 1:2. In addition, it isdesirable to maintain a weight ratio of silver to hydrophilic colloid offrom 1:2 to 1:20, and preferably from 1:3 to 1:15. These ratios providecoatings having suitable physical properties. When weight ratios ofsilver to hydrophilic colloid of less than about 1:2 and coupler tohydrophilic colloid ratios of less than about 1: /z are utilized, thecoatings become extremely soft. When ratios of silver to hydrophiliccolloid higher than about 1:20 are utilized, the advantages of theinvention with respect to increased sharpness, improved granularity,developability, higher speed and reduced fog tend to be minimized.Weight ratios of coupler to hydrophilic colloid higher than 1:2 tend toresult in a loss of sharpness and granularity and decrease the improveddye stability.

The ratios of silver to coupler referred to above are desirable toobtain a suitable sensitometric photographic curve shape and sufiicientdye density.

The elements of this invention are advantageously processed inaccordance with the procedures described in aforementioned U.S. Ser.Nos. 189,289 by Bissonette filed Oct. 14, 1971, and 256,071 by Travisfiled May 23, 1972, now U.S. Pat. 3,765,891, which are both incorporatedby reference. The various oxidizing agents, or oxidants, which can beutilized in combination with photographic aromatic primary aminocolor-developing agents to develop the elements of this invention shouldhave a reactivity with the color-developing agent generally similar tocobalt hexammineflll). The preferred oxidants are the metal complexes,such as a transition metal complex, e.g., a Group VIII metal complex, ora complex of a metal of Series 4 of the Periodic Table appearing on pp.54 and 55 of Langes Handbook of Chemistry, 8th edition, published byHandbook Publisher, Inc., Sandusky, Ohio, 1952. Such complexes feature amolecule having a metallic atom or ion. This metallic atom or ion issurrounded by a group of atoms, ions of other molecules which aregenerically referred to as ligands. The metallic atom or ion in thecenter of these complexes is a Lewis acid; the ligands are Lewis bases.Werner complexes are well-known examples of such complexes. The usefulmetal salts are typically capable of existing in at least two valentstates. In a preferred aspect of the invention, the metal complexes arethose referred to by American chemists as inert and by European chemistsas robust. Particularly useful are complexes of a metal ion with aligand which, when a test sample thereof is dissolved at .1 molarconcentration at 20 C. in an inert solvent solution also containing .1

molar concentration of a tagged ligand of the same species which isuncoordinated, exhibits essentially no exchange of uncoordinated andcoordinated ligands for at least 1 minute'and preferably for at leastseveral hours, such as up to hours or more. This test is advantageouslyconducted under the pH conditions which will be utilized in the practiceof the invention. In silver halide photography, this generally will be apH of about 8 to 13. Many metal complexes useful in this invention showessentially no exchange of uncoordinated and coordinated ligands forseveral days. The definition of inert metal complexes, and the method ofmeasuring ligand exchange using radioactive isotopes to tag ligands, arewell-known in the art. See, for example, Taube, Chem. Rev., vol. 50, p.69 (1952) and Basolo and Pearson, Mechanisms of Inorganic Reactions, AStudy of Metal Complexes and Solutions, 2nd edition, 1967, published byJohn Wile and Sons, p. 141. Further details on measurement of ligandexchange appear in articles by Adamson et al., J. Am. Chem. Soc., vol.73, p. 4789 (1951). The inert metal complexes should be contrasted withlabile complexes which, when tested by the method described above, havea reaction half-life generally less than 1 minute. Metal chelates are aspecial type of metal complex in which the same ligand (or molecule) isattached to the central metal ion at two or more different points. Themetal chelates generally exhibit somewhat slower ligand exchange thannonchelated complexes. Labile-type chelates may have a half-life ofseveral seconds, or perhaps slightly longer. Generally, the'oxidizing,agents employed are not reduced to a zero valent metal during the redoxreaction of the invention.

Preferred metal complexes in accordance with this invention havecoordination numbers of 6 and are known as octahedral complexes. Cobaltcomplexes are especially useful in the practice of this invention. Mostsquare planar complexes (which have a coordination number of 4) arerather labile, although some Group VIII metal square planar complexes,particularly platinum and palladium square planar complexes, exhibitinertness to rapid ligand exchange.

A wide variety of ligands can be used with a metal ion to form suitablemetal complexes. Nearly all Lewis bases (i.e., substances having anunshared pair of electrons) can be ligands in metal complexes. Sometypical useful ligands include the halides, e.g., chloride, bromide,fluoride, nitrite, water, amino, etc., including such common ligands asthose referred to on p. 44 of Basolo et al., supra. The lability of acomplex is influenced by the nature of the ligands selected in formingsaid complex.

Particularly useful cobalt complexes have a coordination number of 6 andhave a ligand selected from the group consisting of ethylenediamine(en), diethylenetriamine (dien), triethylenetetraamine (trien), ammine(NH nitrate, nitric, azide, chloride, thiocyanate, isothiocyanate,water, carbonate and propylenediamine (tn). The preferred cobaltcomplexes comprise (l) at least 2 ethylenediamine ligands or (2) atleast 5 amine ligands or (3) ltriethylenetetraamine ligand. Especiallyuseful are the cobalt hexammine salts (e.g., the chloride, bromide,sulfite, sulfate, perchlorate, nitrite and acetate salts). Some otherspecific highly useful cobalt complexes include those having one of thefollowing formulas:

wherein X represents one or more anions determined by the chargeneutralization rule. Complexes containing oxidized noble metals orferromagnetic metals such as complexes of Cr Fe Rh Pt V, Pd and Ir whichhave reactivities similar to the complexes listed above, could be usedin the practice of this invention. The redox equilibria published inStability Constants of Metal-Ion Complexes, Sillen and Martell,published by The Chemical Society, Burlington House, London, England(1964), indicate that other complexes have reactivities similar to thecobalt complexes mentioned above.

With many complexes, such as cobalt hexammine, the uncoordinated anionsselected can substantially effect the reducibility of the complex. Thefollowing anions are listed in the order to those which give increasingstability to cobalt hexammine complexes: bromide, chloride, nitrite,perchlorate, acetate, carbonate, sulfite and sulfate. Other anions willalso effect the reducibility of the complex. These uncoordinated anionsshould, therefore, be chosen to provide complexes exhibiting the desireddegree of reducibility. Some other uncoordinated anions includehydrochloride, nitrate, thiocyanate, dithionate and hydroxide. Neutralcomplexes such as [Co (dien) (SCN) 0H] are useful, but positivelycharged complexes are generally preferred.

The most useful aromatic primary amine color-developing agents include3-acetamido-4-amino-N,N-diethylaniline,p-amino-N-ethyl-N-(,B-hydroxyethyl) aniline sulfate,N,N-diethyl-p-phenylenediamine, Z-amino-S-diethylaminotoluene,N-ethyl-N- fl-methanesulfouamidoethyl] -3-methylaminoaniline,4-amino-3-methyl-N-ethyl-N-B-methoxyethylaniline,4-amino-N-ethyl-3-methyl-N- ,B-sulfoethyl) aniline, 4-amino-N,N-diethylaniline hydrochloride, 4-amino-3-methyl-N,N-diethylanilinehydrochloride, 4-.arnino-3-methyl-N-ethyl-N-18- (methanesulfonamidoethylaniline sulfate hydrate,4-amino-3-methyl-N-ethyl-N-p-hydroxyethylaniline sulfate,4-amino-3-dimethylamino-N,N-diethylaniline sulfate hydrate,4-amino-3-methoxy-Nethyl-N-fi-hydroxyethylaniline hydrochloride,4-amino-3- 8-(methanesulfonamido)ethyl-N,N-diethylanilinedihydrochloride, 4-amino-N-ethyl-N-(Z-methoxyethyl)-m-toluidinedi-ptoluene sulfonate,

and the like. See Bent et al., JACS, vol. 73, pp. 3100-3125 (1951) forfurther typical, useful color-developing agents. It will be appreciatedthat many of the subject reducing agents are most effective at high pH,such as a pH from about 8 to 13.

The elements of this invention can be processed to provide negative orreversal dye images, form example, using a procedure generally similarto that described in Graham et al., US. Pat. 3,046,129. In reversalprocesses, it is desirable to remove or deactivate the initial negativesilver image prior to contacting the film with color-developer solutioncontaining metal complex in order to prevent undesired interactionbetween developer, metal complex and the initial silver image.

The image dye-providing layer units as described herein are also usefulin diffusion transfer elements. The image dye-providing layer unit cancontain initially immobile couplers or releasable dyes, or the couplerscan be initially mobile. Typical image transfer systems where the imagedye-providing layer units can be used include U.S. Pats. 2,983,606 byRogers issued May 9, 1961; 3,227,552 by Whitman issued Aug. 27, 1964,3,443,940 by Bloom and 3,443,943 by Rogers, both issued May 13, 1969,and 3,415,644, 3,415,645 and 3,415,640, all by Land issued Dec. 10,1968, Belgian Pat. 757,959 by Cole issued Apr. 23, 1971, and U.S. Ser.No. 176,751 by Fleckenstein filed Aug. 8, 1971, now abandoned, and thelike.

The photographic emulsions employed herein can be washed in accordancewith conventional procedures and can contain sensitizers, antifoggants,stabilizers, hardeners, plasticizers, lubricants, surfactants,spectral-sensitizing dyes and other similar photographic addenda. Thephotographic elements can also contain layers which may contain variousantistatic or conducting layers, filters, brightening agents and thelike. The photographic layers can be coated by typical proceduresincluding dip coating, airknife coating, curtain coating, or extrusioncoating using hoppers of the type described in Beguin, U.S. Pat. 2,681,-294 issued June 15, 1954, or by other coating procedures. The elementsof this invention are also suitable for use in colloid transfer andcolor image transfer processes of the type heretofore described in theart.

The photographic image dye-providing layer units can be coated on a widevariety of supports. Typical supports include cellulose nitrate film,cellulose ester film, poly (vinyl acetal) film, polystyrene film, poly(ethylene terephthalate) film, polycarbonate film and related films orresinous materials, as well as glass, paper, metal and the like.Typically, a flexible support is employed, especially a paper support,which can be partially acetylated or coated with baryta and/or anu-olefin polymer, particularly a polymer of an a-olefin containing 2 to10 carbon atoms such as polyethylene, polypropylene, ethylenebutenecopolymers and the like. The color-providing layer units can be coatedon the same side of the support or on opposite sides of the supportwhere desired, such as when using a transparent film support.Photographic elements can be coated with layer arrangements as used formany multicolor elements or they can be coated in the format used forX-ray elements and the like. In the latter case, the eifective spectralsensitivity of the image dye-providing layer units may be the same or itmay be different, depending on which areas of the electromagneticspectrum are desired to be recorded.

The following examples are included for a further understanding of theinvention.

Example 1 illustrates the increase in speed, contrast and dye density,and the reduced fog obtained using the photographic elements andprocesses of this invention.

Example 1 I Ratio Ratio of Gelatin, Ag" to coupler to mg./it. gelatingelatin Coating 1 (prior art) 240 1:4 1:6. 5 Coat ng 2 (invention) 601:11. 5 1:1.6 Coating 3 (invention) 40 1:8 1:1. 1

12 The coatings are given a stepped exposure to red light and then aredeveloped for 7 minutes at 30 C. in the following developer:

Water to 1 liter pH 10.1 at F.

The elements are then bleached, fixed and dried, and the coatings inaccordance with the invention are compared with the prior-art coating(Coating 1) with the following results:

TABLE 1 Fog Speed Contrast Dmu.

Coatlng 2 23 13 +1. 02 2 Coating 3 24 15 92 2 A visual comparison showsthat the images in Coating 1 (prior-art, high gelatin concentration) aremore granular and less sharp than in Coatings 2 and 3 of the inventionwhich employ low gelatin concentrations. Generally, similar results areobtained in each layer of multilayer coatings, such as the typical red-,greenand blue-sensitive silver halide emulsion layers containing,respectively, cyan, magenta and yellow dye-forming photographic colorcouplers. Also, generally similar results are obtained when thephotographic couplers utilized are the Fischer-type couplers, e.g., thenonditfusible Fischer-type couplers containing branch carbon chains,such as those described in Frohlich et al., U.S. Pat. 2,371,679 issuedMay 22, 1945. Also, genereally similar results are obtained when othercolloids are substituted for gelatin.

The unexpected increase in heat stability of dyes formed in the lowvehicle emulsions of the invention is illustrated in Example 2.

Example 2 A series of coatings is prepared as described in Example 1,but using the gelatin, silver and coupler concentration shown in Table2. The dye loss, at a density of 1.0, is measured after storage in a dryoven at 77 C. for 2 weeks. The percentage dye loss is reported in Table2 for each The results in the above table show the increase in cyan dyestability obtained when the vehicle coverage is reduced to amounts belowabout 970 mg./m. This is unexpected since gelatin is generally regardedas contributing to dye stability.

Example 3 Two multilayer coatings are prepared at the concentrations (inmg./m. as shown in Table 3. The silver halide in the light-sensitivelayers is silver chlorobromide (about 15 mole percent chloride and molepercent bromide) having an average grain size of about .3 micron in themagenta and cyan layers and an average grain size of about 1.2 in theyellow layer. The cyan coupler is the same as the one identified inExample 1. The yellow dyeforming coupler is tit-[4 (4benzyloxyphenylsulfonyl) phenoxy]-ot-pivalyl 2 chloro[ot-(2,4-di-tert-amylphenoxy)butyramido] acetanilide and the magentacoupler is 1 (2,4,6 trichlorophenyl) 3 [2 chloro-5-(u-{4- hydroxy 3tert-butylphenoxy}tetradecanamido)amino]- S-pyrazolone. The cyan andyellow couplers are dissolved in dibutyl phthalate coupler solvent at aweight ratio of about 1: /2 and l:% (couplerzsolvent) respectively, andthe magenta coupler is dissolved in tricresyl phosphate coupler solventat a weight ratio of 1: /2 (coupler:sol vent).

TABLE 3 Gelatin Coupler Silver Coat- Ooat- Cqat- Coia't- Cqat- Coatmg mgmg mg mg mg Support The coatings are given red-, greenandblue-sensitometric exposure, developed with the developer solution usedin Example 1, bleached, fixed, washed and dried. The fog values aregiven in Table 4:

TABLE 4 Prior-art Invention coating 1 coating 2 A Fog Example 4 Onesample of each of the two multilayer coatings prepared and exposed asdescribed in Example 3 are processed in the following sequence:

Color-develop 0.5 min. 40 C. Amplify 1.5 min.-40 C. Bleach-fix 1min.-40C. Wash 1.5 min.--2'6 C.

The processing baths are as follows:

Color Developer Benzyl alcohol ml 15 5 K 80 g 4 KBr g 0.4 Hydroxylaminesulfate g 2 4-amino-N-ethyl-N-(Z-methoxyethyl)-m-toluidinedipara-toluenesulfonate g 7.5 K CO g Diaminopropanol tetraacetic acid g5 Water to 1 liter pH 10.1

Amplifier 5 Benzyl alcohol ml [Co(NH )6]C1 g 10 KBr g 2 K C0 g 7.5 K2803g Diaminopropanol tetraacetic acid "g 10.0 Water to 1 liter pH 10.1

Bleach-Fix 25 Diaminopropanol tetraacetic acid g 3 Acetic acid ml 20(NH4)2S2O3 m1 Na SO g [C0(NH )6]Cl g 3 Water to 1 liter The low gelatincoating (Coating 2) shows improvements over the high gelatin coating(Coating 1) when processed as above which are similar to those mentionedin Example 3.

Example 5 The coatings of Example 3 are kept for 1 year under averageroom keeping at a temperature of 24 C. and then processed as describedin Example 4. The same advantages are observed as listed in Example 3,especially with regard to the cyan image. In particular, it is observedthat the minimum densities of the image dyes in the highgelatin coatingare much higher than in the low-gelatin coating as shown in thefollowing table:

TABLE 5 Highgelatin Low-gelatin coating, Dmin. coating, Dmin.

Cyan 22 17 ellow In certain embodiments of this invention it isdesirable to coat the silver halide layer separately and to havecontiguous on each side thereof a layer containing the color coupler,which layers form the image dye-providing layer unit. Examples 6 and 7set forth structures of this type where improved photographic propertiessuch as speed, granularity and the like are observed.

Example 6 Three film elements containing magenta image dye-providinglayer units are coated on a cellulose acetate film support containing acarbon black antihalation layer. The elements are prepared as follows:

2. layer containing 66 mg/ft. of coupler A dispersed 1:1 in tricresylphosphate and 73 mg./ft. of gelatin;

3. layer containing 24 mg./ft. of AgClBr based on Ag and 73 mg./ft. ofgelatin;

4. layer containing 66 mg./ft. of coupler A dispersed 1:1 in tricresylphosphate and 73 mg./ft. of gelatin.

Element C:

1. support;

2. layer containing 66 mg./ft. of coupler A dispersed 1:1 in tricresylphosphate and 66 mg./ft. of gelatin;

3. layer containing 24 mg./ft. AgClBr based on Ag and 10 mg./i:'t. ofgelatin;

4. layer containing 66 rng./ft. of coupler A dispersed 1:1 in tricresylphosphate and 66 mg./ft. of gelatin.

Each of the elements is exposed in a sensitometer and processed at 38 C.as follows:

4 amino 3 methyl N,N diethylaniline hydrochloride 3.0

Na2CO3 NaBr 1.0 Ethylenediaminetetraacetic acid, sodium salt 1.0

H to 1 liter pH 10.75 at 75 F.

The developer-amplifier has the same formula as the developer next abovewith the addition of 1.6 g./l. of 3)e] 3- The bleach-fix is:

Diaminopropanol tetraacetic acid g.. 3 Acetic acid ml 20 60% (NH S O ml150 Na SO g 3)e] 3 g 3 Water to 1 liter The speeds of the developedimages are substantially identical and the fog is within 0.06 densityunit for all samples. The gamma in all cases is approximately 1.0. TheRMS granularity is measured at equal density points by the proceduredescribed by Altman, Applied Optics, The Measurements of RMSGranularity, pp. 35-38, 1963, and is recorded for each sample as o'(D).

RMS Granularitye(D) Element A .0065 Element B .0044 Element C .0045

There is a substantial improvement in granularity with Elements B and Cwith equivalent speed and sharpness. Similar improvements in granularityare obtained when the yellow image dye-providing layer, the cyan imagedyeproviding layer and the magenta image dye-providing layer of amulticolor integral-layer photosensitive silver halide element arecoated with layers containing the respective coupler contiguous on eachside of the silver halide emulsion layer.

Example 7 Two film elements containing magenta image dyeproviding layerunits are coated on a paper support as follows:

Element A (control):

1. support;

2. layer containing 159 mg./ft. of gelatin, 35 mg./

ft. of a-[a-( 2,4-di-tert-amylphenoxy)butyramido1- 4,6-dichloro-5-methylphenol dispersed 1:1 in tricresyl phosphate, and 5.25 mg./ft. of AgClBrbased on silver.

Element B:

1. support;

2. layer containing mg./ft. of gelatin and 18 mg./ft. of2-[a-(2,4-di-tert-amylphenoxy(butyramido] 4,6 dichloro-S-methyl phenoldispersed 1:1 in tricresyl phosphate;

3. layer containing 5.25 mg./ft. of AgClBr based on silver and 2 mg./ft.of gelatin;

4. layer containing 80 mg./ft. of gelatin and 18 mg./ft. of2-[a-(2,4-di-tert-amylphenoxy)butyramido] 4,6 dichloro-S-methyl phenoldispersed 1:1 in tricresyl phosphate.

The elements are given a red-light exposure on a sensitometer anddeveloped to identical gamma and fog by the process of Example 1.Element B is 0.3 log exposure faster than Element A.

Example 8 Multilayer coatings are made as described in Example 3 whereinthe blue-, greenand red-sensitive silver halide emulsions containrespectively 16, 10 and 6 mg. of silver/ ft. of coating. Theconcentrations of the couplers are varied according to the matrix asfollows:

Coupler Coupler equivalency/ concentration, Ag equivmgJit. alentsImagewise-exposed samples are processed by the procedures of Examples 3and 4. Good color reproduction is obtained with all samples with thebest results occurring when the coupler-to-actual-silver ratio is 1:1.4or greater, especially using this ratio in the cyan and magenta layers.

Although the invention has been described in considerable detail withparticular reference to certain preferred embodiments thereof,variations and modifications can be effected within the spirit and scopeof the invention.

We claim:

1. In a photographic element comprising a support having coated thereonat least one image dye-providing layer unit containing a light-sensitivephotographic silver halide emulsion coated at a coverage of up to 320mg. silver/m. and a photographic color coupler at a concentration of atleast two times the weight of the silver, the improvement wherein saidsilver halide and said coupler are dispersed in said layer unit in ahydrophilic colloid with said hydropholic colloid coated at a coverageof from about 215 to 970 mg./m.'-, the Weight ratio of silver tohydrophilic colloid being from 1:2 to 1:20 and the weight ratio of saidcoupler to said hydrophilic colloid being from 1: /2 to 1:2.

2. A photographic element as defined in Claim 1 wherein said hydrophiliccolloid is coated at a coverage of about 215 to 800 mg./m. said silverhalide is coated at a silver coverage of about 55 to 270 tug/m. and said17 coupler is coated at a concentration of about 215 to 1080 mg./m.

3. In a photographic element comprising a support having coated thereonseparate, overlying image dye-providing layer units which respectivelycontain silver halide emulsion sensitive to blue, green and redradiation and, respectively, yellow, magenta and cyan dye-formingphotographic color couplers, and said green and red light-sensitivesilver halide emulsion layers are each coated at a silver coverage of upto about 270 mg./m. and contain photographic color coupler at aconcentration of from 3 to 15 times the weight of the silver therein,the improvement wherein said green and red silver halide-containinglayer units each comprise a hydrophilic colloid coated at a coverage offrom about 215 to 1080 mg./m. the weight ratio of said silver to saidhydrophilic colloid being from about 1:2 to 1:20 and the weight ratio ofsaid coupler to said hydrophilic colloid is from about 1: /2 to 1:2.

4. A photographic element according to Claim 1 wherein said imagedye-providing layer unit is a single layer containing said silver halideemulsion and said coupler coated together with said hydrophilic colloid.

5. A photographic element according to Claim 1 wherein said imagedye-providing layer unit comprises a layer containing a silver halideemulsion having layers contiguous on each side thereof containing saidcoupler.

6. A photographic element according to Claim 1 wherein said imagedye-providing layer contains at least a 40% stoichiometric excess ofimage dye-providing color coupler based on effective silver.

7. A multicolor photographic element according to Claim 1 which containsa cyan image dye-providing layer unit and a magenta image dye-providinglayer unit wherein the respective color coupler in said layer unit ispresent in at least a 40% stoichiometric excess based on silvercoverage.

8. In a photographic element comprising a support having coated thereonseparate, overlying silver halide emulsion layers sensitive to blue,green and red radiation, respectively, each of said emulsion layersbeing coated at a coverage of up to about 320 mg. silver/m said layerscontaining, respectively, yellow, magenta and cyan dye-formingphotographic color couplers in a concentration, in each of said layers,of at least three times the weight of the silver therein, theimprovement wherein each of said silver halide emulsion layers containsfrom about 215 to 970 mg. of a hydrophilic colloid binder/m3, the weightratio of silver to hydrophilic colloid in each of said layers being from1:2 to 1:20, and the weight ratio of the coupler to hydrophilic colloidin each of said layers is from l: /2 to 1:2.

9. A photographic element as described in Claim 8 wherein saidhydrophilic colloid is gelatin, said hydrophilic colloid is coated, ineach layer. at a coverage of about 215 to 8.00 mg./m. the silvercoverage in each of said layers is from about 22 to 160 mg./m. and saidblueand green-sensitive layers are coated between said support and saidred-sensitive layer.

10. A photographic element comprising a support having coated thereon,in the order given, separate, overlying silver halide emulsion layerssensitive to blue, green and red radiation, respectively, each of saidemulsion layers being coated at a silver coverage of up to about 320mg./m. said layers containing, respectively, yellow, magenta and cyandye-forming couplers in a concentration, in each of said layers, of from3 to 15 times the weight of the silver therein, each of said silverhalide emulsion layers containing from about 215 to 97 mg. of gelatinbinder/m. and a weight ratio of coupler to bydrophilic colloid of from12 /2 to 1:2.

11. A photographic element as described in Claim wherein the totalamount of gelatin in said light-sensitive silver halide layers is lessthan about 2700 mg./m.

12. A photographic element as described in Claim 11 wherein saidphotographic element contains a gelatin interlayer between said blueandgreen-sensitive silver halide emulsion layers, said gelatin interlayerbeing coated at a coverage of from about 540 to 1080 mg. gelatin/m2, anultraviolet-absorbing layer comprising gelatin and an ultravioletabsorber coated between said greenand redsensitive silver halideemulsion layers, said ultravioletabsorbing layer containing from about1500 to 2150 mg. gelatin/m and a gelatin overcoat coated at a coverageof from about 540 to 1080 mg./m. the total amount of gelatin in saidphotographic element being less than about 8100 mgJrnP.

13. A process for providing photographic images in an exposedphotographic element comprising a support having coated thereon at leastone image dye-providing layer unit comprising a light-sensitivephotographic silver halide emulsion coated at a coverage of up to about320 mg. silver/m. and a color coupler at a concentration of at least twotimes the weight of the silver, the silver halide and the coupler beingdispersed in a hydrophilic colloid coated on said support at a coverageof from about 215 to 970 mg./m. the weight ratio of silver tohydrophilic colloid being from 1:2 to 1:20 and the weight ratio of saidcoupler to said hydrophilic colloid being from l: /2 to 1:2, whichcomprises developing said exposed photographic element with a developersolution comprising a photographic aromatic primary aminocolordeveloping agent and an oxidizing agent which undergoes redoxreaction with said color developing agent in the presence of metallicsilver, Said color-developing agent and said oxidizing agent beingessentially inert to redox reaction in the absence of a catalyticmaterial, said oxidizing agent and said color-developing agent being sochosen that the reaction products thereof are noncatalytic for saidredox reaction.

'14. A photographic process as defined in Claim 13 wherein saidoxidizing agent is a metal complex.

15. A photographic process as defined in Claim 14 wherein said oxidizingagent is a cobalt complex having a coordination number of 6.

16. A process according to Claim 13 wherein said photographic elementcomprises at least one layer unit wherein said color coupler is presentin at least a 40% stoichiometric excess based on silver.

17. A process according to Claim 13 wherein said image dye-providinglayer uni-t comprises a layer containing a silver halide emulsion havinglayers contiguous on each side thereof containing said coupler.

18. A process according to Claim 13 wherein said image dye-providinglayer unit is a single layer containing said silver halide emulsion andsaid coupler coated together with said hydrophilic colloid.

19. A process of providing photographic images in an exposedphotographic element comprising a support having coated thereonseparate, overlying silver halide emulsion layers sensitive to blue,green and red radiation and containing, respectively, yellow, magentaand cyan dyeforming photographic color couplers, each of saidlightsensi-tive silver halide emulsion layers being coated at a silvercoverage of up to about 270 mg. silver/ m? and containing saidphotographic color couplers in an amount of from about 3 to 15 times theweight of the silver, each of said light-sensitive layers comprising ahydrophilic colloid coated at a coverage of from about 215 to 1080 mg./m the weight ratio of silver to hydrophilic colloid being from 1:2 to1:20 and the weight ratio of coupler to hydrophilic colloid being fromabout l: /2 to 1:2 in each of said layers, which comprises developingsaid exposed photographic element in a photographic developing solutioncomprising a photographic aromatic primary amino color-developing agentand an oxidizing agent which undergoes redox reaction with saidcolor-developing agent in the presence of silver catalyst, saidcolor-developing agent and said oxidizing agent being essentially inertto oxidation-reduction reaction in the absence of catalytic material,and said oxidizing agent and said color-developing agent being so chosenthat the reaction products thereof are noncatalytic for saidoxidation-reduction reaction.

20. A photographic process as defined in Claim 19 wherein said oxidizingagent is a cobalt complex having a coordination number of 6.

21. A photographic process as defined in Claim 15 wherein said cobaltcomplex comprises a ligand selected from the group consisting ofethylenediamine, diethylenetriamine, triethylenetetraamine, amine,nitrate, nitrite, azide, chloride, thiocyanate, isothiocyanate, waterand carbonate, said complex comprising (1) at least 2 ethylenediamineligans or (2) at least 5 amine ligands or (3) at least 1triethylenetetraamine ligand.

22. A photographic process as defined in Claim 19 wherein said cobaltcomplex is cobalt hexammineQIII) chloride.

23. A photographic element as defined in Claim 3 wherein silver halidein said greenand red-sensitive layers is coated at a coverage of up toabout 110 mg. silver/m 24. A process for providing photographic imagesin an exposed photographic element comprising a support having coatedthereon at least one image dye-providing layer unit comprising alight-sensitive photographic silver halide emulsion coated at a coverageof up to about 320 mg. silver/m and a color coupler at a concentrationof at least two times the weight of the silver, the silver halide andthe coupler being dispersed in a hydrophilic colloid coated on saidsupport at a coverage of from about 215 to 970 mg./ rn. the weight ratioof silver to hydrophilie colloid being from 1:2 to 1:20 and the weightratio of said coupler to said hydrophilic colloid being from l: /2 to1:2, which comprises developing said exposed photographic element toform an imagewise distribution of developed metallic silver andundeveloped silver halide and providing contact of said element with anaqueous liquid in the presence of an aromatic primary aminocolor-developing agent and an oxidizing agent which undergoes a redoxreaction with said color-developing agent in the presence of metallicsilver, said colordeveloping agent and said oxidizing agent beingessentially inert to redox reaction in the absence of a catalyticmaterial, said oxidizing agent and said color-developing agent being sochosen that the reaction products thereof are noncatalytic for saidredox reaction.

25. A photographic process as defined in Claim 24 wherein said oxidizingagent is a metal complex.

26. A photographic process as defined in Claim 24 wherein said oxidizingagent is a cobalt complex having a coordination number of 6.

References Cited UNITED STATES PATENTS 2,875,052 2/1959 Edith 96683,551,151 12/1970 Rodwick 9674 RONALD H. SMITH, Primary Examiner ALFONSOT. SURO PICO, Assistant Examiner U.S. Cl. XJR.

96- 55, R, 60 BF, 66 R, 74

, mg? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIGN Patent No.3322.129 Dated Julv 2. 1974 Inventot'(s) Joseph S. Dunn and Rowland G.Mowrey ls is certified that error appears in the above-identified patentend that said Letters-Patent are hereby corrected as shown below:

Column 3, line 52,.after "obtain", the should reed a a Column 5, line13, "accomplishd" should read :;oc'omplisl'led a Column 9, line 54,"nitrie" should read --nitrice--; line 58 "l--" should read w l Column10, line L "[Co(tn-)-(en) jX" should read --[Co(on) (en)2]X--; line9,"Pt V' should read VPt line 20,af ter "order", "to" should read--of--; line 65, "form" should read --for--. Column 11, line 64, after"coverage", --ofshould be inserted. Column 12, line 39,

"genereally" should read --generally--. Column 17, line 11,

after "from", --aboucshould be inserted. Column 19, line 15,

"ligens" should read --ligands--. Column 20, line 25, "Edith" shouldread --Weyde--; line 26, "Rodwiek" should read -Malau--,.

Signedland sealed this 26th day of November 1974.

(SEA

Attest:

MeCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents

